Left 4 Dead 2

so i got this game yesterday and i played it a little and then it crashesso i click play and it says this'this game is unavailable, please try another time'so i wait for A DAYand it still has this errorplease tell me how to fix!

That happends to me too with different games, I have no idea what causes it, it just eventually works after some time, could be days. You could try re-installing steam, other than that just wait it out.

Sounds like an issue with it validating or perhaps it needs to defrag? If you have add-ons installed from the workshop, uninstall all of them. I have had so many issues with add-ons. The issue with it crashing could also be that the game didn't get installed correctly. If that is the issue then you should just delete it and reinstall. I know that's a pain in the 'bass', but it may be the only way. Any other issues that would cause the game to do that is either your computer is just messing up (drivers and what not), or another application is conflicting with your game. I would upgrade all drivers, windows itself, and any other applications. Antivirus software can cause issues, but it is unlikely. If none of that works, contact Valve. They would know what to do.

4. Exit Steam and delete everything under the Steam installation directory except Steam.exe, the ClientRegistryOld.blob, and the \SteamApps folder - this will force Steam to update when you log in

5. Complete the Verifying GCF Cache Files process to repair your game cache files.This error may be caused by having certain Steam files set to Read Only. To resolve this:Exit Steam.

Navigate to the directory where you have installed Steam. (Typically C:\Program Files\ or C:\Program Files\Valve\.)

Right-click on the Steam folder.

Select Properties.

Check the Read-Only checkbox and press Apply.

Uncheck the Read-Only checkbox and press Apply.

7. If this issue is only happening on a third party non-Valve game, please try launching the game's .exe directly from its installation folder: C:\Program Files\Steam\SteamApps\Common\<Game Title>. You may also try other .exe's such as Launcher.exe in the game folder to see if a different error message is found.

4. Additionally, you will want to add any .exe's for the game you are seeing issues with. These files will either be in Steam\steamapps\common\<Game Title> or in \Steam\steamapps\<Your Steam Account Name>\<Game Title>\